#include<stdio.h>
int main()
{
    int x,y;
    scanf("%d",&x);
    if(x>=3 && x<=9)
    y=x*(x+2);
    else if(x>=-1 && x<3)
    y=2*x;
    else if(x<=-1)y=x-1;
    else y=-1;
    printf("%d\n",y);
    return 0;
}